Actor Russell Johnson , best known as Professor in the 1960s TV sitcom `` Gilligan 's Island , '' died Thursday , his agent said . Johnson was 89 .

Johnson played the iconic role of Professor Roy Hinkley , whose scientific schemes to get the castaways rescued were always foiled by Gilligan 's bumbling .

He died at his home in Washington , where he lived with his wife , Connie . She and their daughter , Kimberly , were at his side , said agent Mike Eisenstadt . Johnson is also survived by a stepson , Court , and a grandson , he said .

Johnson worked up until his death , signing autographs over the holidays , said Eisenstadt . He called Johnson 's death `` unexpected . ''

The chief deputy coroner in Kitsap County , Washington , told CNN that Johnson died from natural causes .

Johnson was `` just a positive and nice guy '' who always treated people with respect , his agent said .

His acting career began in the early 1950s with many jobs as a character actor on television . He played Marshal Gib Scott in two seasons of `` Black Saddle , '' a Western that ran in 1959 and 1960 .

Johnson acted in dozens of television shows after the four seasons on `` Gilligan 's Island , '' but his career seemed stranded on its own island because of the popular sitcom role .

A noteworthy big screen role was as a nuclear physicist in the 1955 science fiction film `` This Island Earth . ''

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Johnson was in Ray Bradbury 's 1953 sci-fi classic `` It Came From Outer Space . ''

Before becoming an actor , Johnson served in the U.S. Army Air Forces during World War II . He was on a B-24 Liberator when it was shot down during a bombing raid over the Philippines in 1945 , according to his official biography , and used his G.I. Bill benefits to pay for acting school after the war .

Johnson , in a 2004 interview for the Archive of American Television said the success of `` Gilligan 's Island , which he never expected to last more than the initial order of 13 episodes , was the result of the `` great chemistry '' of the cast .

Tina Louise , who played the glamorous Hollywood starlet Ginger on `` Gilligan 's Island said she was '' very saddened to hear of the passing of Russell Johnson . ''

`` My prayers and condolences go out to his wife Constance and his family , '' Louise said . `` He will always be in our hearts and remembered from Gilligan 's island as part of American pop culture history . He will truly be missed . ''

Advice to young actors

Johnson 's advice to young actors was to `` prepare yourself . ''

`` Most of us have to really learn how to do what we do , and that takes some studying and being part of an acting group , '' he said . `` Preparation is everything , and that means studying . ''

Another important ingredient to acting success is perseverance , he said . `` You can have all the talent in the world , but if you do n't persevere , if you do n't stick to it , it does n't mean anything . ''

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Johnson played the iconic role of Professor Roy Hinkley on `` Gilligan 's Island ''

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Johnson worked up until his death , signing autographs over holidays

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He was `` just a positive and nice guy , '' his agent says

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Johnson , 89 , was an Army Air Forces veteran of World War II